Evaluation of Methylene Blue in Cardiothoracic Surgery-Related Vasoplegic Shock

Introduction: Methylene blue has been proposed as an off-label, adjunct treatment option for vasoplegic shock by increasing vascular smooth muscle tone and reducing vasodilation. In the past 5 years, Memorial Hermann Memorial City Medical Center has seen increased utilization of methylene blue. This study evaluates methylene blue use and identifies potential reasons for increased utilization.


Methods: This is a single-center retrospective chart review of adult patients who received at least a single dose of methylene blue following major cardiothoracic surgery. The historical cohort included patients who received a dose from January 1, 2019 through December 31, 2020. The current cohort included patients from January 1, 2022 through December 31, 2023. The primary objective is to characterize the degree of hemodynamic instability prior to administering methylene blue by using the Vasoactive-Inotropic Score. Secondary objectives are time to discontinuation of all vasoactive medications, hospital and intensive care unit length of stay, and mortality. We also assessed the dosing strategies of methylene blue.


Results: A total of 79 patients were evaluated, 7 in the historical group and 72 in the current group. Baseline characteristics were similar between groups. The median baseline VIS and norepinephrine equivalent dose were significantly lower in the current group (25.7 vs 8.2; P< 0.01 and 0.30 vs 0.11 mcg/kg/min; P< 0.01, respectively). Methylene blue use increased 10-fold over the past five years with dosing not being consistent with the recommended weight-based dosing according to literature. Methylene blue did not significantly improve mean arterial pressure (80 vs 69 mmHg; P=0.09) and central venous pressure (16 vs 11 mmHg; P=0.07) in either group one hour after administration. The median time to discontinuation of all vasoactive medications was no different between groups (2.1 vs 1.6 days; P=0.39).


Conclusions: Recent use suggests that methylene blue is administered in more hemodynamically stable patients compared to historical use. Furthermore, dosing strategies are inconsistent. Findings also show that methylene blue use between the groups did not have a substantial impact on efficacy outcomes. Criteria for use of methylene blue as an adjunct therapy may need to be established to ensure appropriate use.